Master paper winding drum in electrophotographic copying machine of contact printing type

ABSTRACT

Apparatus for electrophotostatically placing the image of the indicia of an original onto a master sheet and transferring the image to a copy sheet. The apparatus includes a drum having a resilient layer and a flexible electrically conductive outer layer on which the master sheet is mounted.

United States Patent [191 Inagaki 1 1 MASTER PAPER WINDING DRUM INELECTROPHOTOGRAPI-IIC COPYING MACHINE 0F CONTACT PRINTING TYPE [76]Inventor: Keiichi Inagaki, 4-12 Goshikiyama 7-chome, Taramiku Kobe,Japan [22] Filed: Jan. 23, 1974 [21] Appl. No.: 435,989

[52] US. Cl. 355/12 [51] Int. Cl G03g 15/00 [58] Field of Search 355/3R, 12, 17, 3;

[56] References Cited UNITED STATES PATENTS 3,490,842 1/1970 Reick et355/12 X July 8,1975

3,612,680 10/1971 Macklem 355/11 3,689,144 9/1972 Kaufman 355/3 RFOREIGN PATENTS OR APPLICATIONS 122,488 2/1958 U.S.S.R 355/12 1,193,41711/1959 France 355/12 Primary Examiner-John M. Horan Attorney, Agent, orFirmA. Yates Dowell 5 7 ABSTRACT Apparatus for electrophotostaticallyplacing the image of the indicia of an original onto a master sheet andtransferring the image to a copy sheet. The apparatus includes a drumhaving a resilient layer and a flexible electrically conductive outerlayer on which the master sheet is mounted.

3 Claims, 4 Drawing Figures 1 MASTER PAPER WINDING DRUM INELECTROPIIOTOGRAPHIC COPYING MACHINE OF CONTACT PRINTING TYPE SUMMARY OFINVENTION The preferred embodiment of the present invention overcomesthe problem of difficulty to reproduce an image of sufficiently finelines by providing an apparatus, that is. a rotating cylinder forprinting in an elecrophotograph machine, which comprise a centralcylinder composed of a rigid material, an intermediate coating layercomposed of an elastic material rich in softness and stretchability, andan outermost layer composed of a thin metal plate or metal net or avacuum evaporation deposited metal.

DETAILED DESCRIPTION OF INVENTION This invention relates to anelectrophotographic copying machine of the contact printing type inwhich a master paper wound on the peripheral surface ofa rotary drumrotating in the state circumscribed with a light exposure drum issubjected to such operations as charging, light exposure, development,transfer and cleaning.

FIGS. I and 2 are views showing operation systems of knownelectrophotographic copying machines of the contact printing type. FIG.3 is a view illustrating the section of the rotary drum of thisinvention. FIG. 4 is a view illustrating the operation system of theelectrophotographic copying machine provided with the rotary drum ofthis invention.

FIG. 1 illustrates an electrophotographic copying machine of the knowncontact printing type, in which a master paper mp rotated in an endlessmanner by means of a plurality of rollers r is charged in a chargingzone E, then the master paper is travelled in the state contacted withan original ms on the periphery of a glass cylinder g for light exposureby means of a belt V forwarded by a belt-driving device, to therebyeffect printing, and then the master paper is subjected to a series ofoperations such as development and transfer in zones D and T. FIG. 2illustrates another known type of an electrophotographic copyingmachine, in which, as in the case of this invention, a master paper mpis wound on a metal drum md, this metal drum is rotated in the statecontacted with a light exposure cylinder, and a series of operationssuch as charging, light exposure, development, transfer and imageerasing are performed during one rotation of the metal drum.

In the electrophotographic copying machine shown in FIG. 1, since therunning passage of the master paper is curved and long, meandering andslip are readily caused to occur, and it is therefore difficult to placean original on the running master paper in such a manner that the imageof the original is not placed on a joint of the starting and terminalends of the master paper. This is one of the defects involved in theelectrophotographic copying machine of the type shown in FIG. 1. Theelectrophotographic copying machine shown in FIG. 2 involves none ofsuch defect, but since the metal drum rnd is circumscribed with thelight exposure cylinder with a linear contact, if the light exposurecylinder is composed of glass, non-uniformity of the size accuracyinevitable in ceramic articles is brought about in the cylinder and thisnon uniformity has bad influences on the resulting image. With a view toovercoming this disadvantage, a cylinder of a plastic material issometimes employed, but this plastic cylinder is readily scarred on thesurface because of an insufficient hardness and it is deriorated byultraviolet rays during long time use, resulting in reduction of lighttransmission. Further, since the contact between the light exposurecylinder and the metal drum is a very precise line contact, the contactarea is very small and it is difficult to reproduce an image of finelines sufficiently. These are defects of the electrophotographic copyingma chine shown in FIG. 2.

It is an object of this invention to improve the rotary drum on which amaster paper is wound in the known copying machine of the type shown inFIG. 2 and overcome the foregoing defects involved in the copyingmachine of this type while retaining merits of this copying machine.

In the known copying machine shown in FIG. 2, the rotary drum on which amaster paper is wound is composed ofa metal. One reason is that themetal is a material which can be processed according to the precisionmethod. The other reason is that the metal has a con ductivity necessaryfor the charging operation.

In view of the foregoing, the master paper winding drum of thisinvention has been achieved. More specifically, as is illustrated inFIG. 3, the central portion of the drum is composed of a cylinder I of ametal or a rigid material, an elastic material 2 having a richstretchability such as sponge rubber or the like is coated on saidcylinder 1, and a thin metal layer or metal net or a vacuum evaporatedmetal is disposed on the coating 2 as an outermost layer 3. In themaster paper winding drum of this invention having the above structure,the conductivity necessary for charging the master paper is provided bythe outermost thin metal layer, and by virtue of the presence of theintermediate layer of the elastic material rich in stretchability thecontact between the drum and light exposure cylinder is not linear but aband-like face-to-face contact is attained.

When the rotary drum of this invention is employed, the master paper isforwarded on the fixed passage in the state wound and fixed on the drum,and therefore, there is no apprehension that meandering or slip of themaster paper is caused to occur during transporation of the master paperas in the machine of FIG. 1. Further, a mechanism is mounted so that anoriginal is not placed on the joint of the starting and terminal ends ofthe master paper. Therefore, transportation of the original andinterchange of the master paper can be greatly facilitated. Moreover,since a layer of an elastic member rich in stretchability such as spongerubber is formed as the intermediate layer, the contact between thelight exposure cylinder and rotary drum can be converted to aface-to-face contact by contraction of the intermediate layer if thethickness of the intermediate layer is adjusted appropriately, andhence, it is possible to reproduce an image of fine lines completely.Still further, even when the light exposure cylinder is composed ofglass inclusive of distortion brought about during the manufacturingstep, a clear copied image can be obtained with no fading, and it isunnecessary to heighten the size accuracy as strictly as in theconventional machine and therefore, the manufacturing cost can bereduced. Still in addition, since a thin metal plate or net or a vacuumevaporated metal layer, which is composed of stainless steel or phosphorbronze, is formed as the outermost layer, the charging operation can beperformed without a trouble. Thus, all of the defects and disadvantagesinvolved in the above mentioned known conventional machines can beovercome in this invention.

FIG. 4 is a view illustrating the entire operation system of the copyingmachine in which the rotary drum of this invention is provided. In FIG.4, symbols 4, D, T. cl and ch indicate a light exposure glass cylinder,a development device, a transfer device, an image erasing device and acharging device, respectively.

What is claimed is:

I. In an electrophotostatic copying machine of the contact printing typein which images on an original paper are copied on a master paper woundaround a master drum, and subsequently transferred to a copy paper, andin which the master drum respectively advances the master paper to acharging means, a light ex posure means, a developing means, transfermeans, and an image erasing means disposed in series around and adjacentthe master drum, the improvement comprising the master drum having arigid central cylinder, an intermediate resilient coating layer disposedaround said central cylinder and a thin metallic outer layer disposedover said resilient layer whereby the outer surface of the master drumis both yieldable and conductive.

2. An electrophotostatic copying machine of the contact printing typecomprising a drum having a rigid central cylinder, an intermediateresilient layer disposed about said central cylinder and a thin flexibleelectrically conductive outer layer carried by said resilient layer sothat the outer surface of said drum is yieldable and electricallyconductive, a master sheet mounted on said outer layer of said drum,electrical charging means located adjacent to said drum for imparting anelectrical charge to said master sheet, light exposure means disposedadjacent to said drum for transferring an image of the indicia carriedby an origi nal onto said master sheet, said light exposure means beingin intimate contact with said drum to cause a portion of said outerlayer to be deflected and a portion of said intermediate layer to becompressed, means for moving said original between said drum and saidlight exposure means, means for selectively operating said originalmoving means so that the image of the original is placed in apredetermined position on the master sheet, an image developing meanslocated adjacent to said drum for developing the image on said mastersheet, transfer means located adjacent to said drum. means for moving asecond sheet through said transfer means so that the image on said drumis transferred to said second sheet, and erasing means adjacent to saiddrum for removing the image from said master sheet after the image hasbeen transferred to said second sheet, whereby an image of the indiciacarried by an original is placed on a master sheet and transferred to asecond sheet after which the image is erased from said master sheet.

3. The structure of claim 2 in which said thin flexible outer layer is ametallic net.

1. In an electrophotostatic copying machine of the contact printing typein which images on an original paper are copied on a master paper woundaround a master drum, and subsequently transferred to a copy paper, andin which the master drum respectively advances the master paper to acharging means, a light exposure means, a developing means, transfermeans, and an image erasing means disposed in series around and adjacentthe master drum, the improvement comprising the master drum having arigid central cylinder, an intermediate resilient coating layer disposedaround said central cylinder and a thin metallic outer layer disposedover said resilient layer whereby the outer surface of the master drumis both yieldable and conductive.
 2. An electrophotostatic copyingmachine of the contact printing type comprising a drum having a rigidcentral cylinder, an intermediate resilient layer disposed about saidcentral cylinder and a thin flexible electrically conductive outer layercarried by said resilient layer so that the outer surface of said drumis yieldable and electrically conductive, a master sheet mounted on saidouter layer of said drum, electrical charging means located adjacent tosaid drum for imparting an electrical charge to said master sheet, lightexposure means disposed adjacent to said drum for transferring an imageof the indicia carried by an original onto said master sheet, said lightexposure means being in intimate contact with said drum to cause aportion of said outer layer to be deflected and a portion of saidintermediate layer to be compressed, means for moving said originalbetween said drum and said light exposure means, means for selectivelyoperating said original moving means so that the image of the originalis placed in a predetermined position on the master sheet, an imagedeveloping means located adjacent to said drum for developing the imageon said master sheet, transfer means located adjacent to said drum,means for moving a second sheet through said transfer means so that theimage on said drum is transferred to said second sheet, and erasingmeans adjacent to said drum for removing the image from said mastersheet after the image has been transferred to said second sheet, wherebyan image of the indicia carried by an original is placed on a mastersheet and transferred to a second sheet after which the image is erasedfrom said master sheet.
 3. The structure of claim 2 in which said thinflexible outer layer is a metallic net.